1. Field of the Invention
This invention relates principally to designer's triangles, and more particularly to triangles wherein a single implement has the capabilities of most of the known triangles, and thus eliminates the need for the use of at least two different triangles to perform designated tasks.
2. Description of the Prior Art
There are numerous triangles and protractors known in the art, and many are commercially available. One common form includes means for setting an adjustable angle which can be used to produce many different angles, as well as read angles off of drawings. Such equipment, however, is obviously subject to shifting and moving, if not exactly positioned or tightened, and thus requires a great deal of care in order to prevent errors in making drawings. In addition, in classroom drafting situations, protractors that have a plurality of holes, variable curvature arcs, a scale, and a few defined angles are well known. However, this type of unit does not provide for the production of numerous angles, and requires other equipment to produce drawings with angles other than the normal 30 and 45 degree angles provided on these units.
U.S. Pat. No. 2,080,620 discloses a drafting implement providing 15, 30, 45, 60, and 90 degree angles but, due to its four-sided "boomerang" shape, it only allows for a 15 degree angle from the horizontal. Additionally, due to its shape, a straight edge is not provided along two of the sides for use directly adjacent a tee square. Thus this instrument lacks the versatility of a triangular instrument, and other devices would be needed for efficient designing and drafting.